There is a growing trend in the bicycling community to use a torque-measuring device mounted to the bicycle that continuously sends information to a display that the rider can easily monitor while riding. The torque-measuring device may compute the torque applied by the bicycle rider to the bicycle drive train. The measured torque may be converted into a power measurement which is shown to the rider on a bicycle computer display.
U.S. Pat. No. 7,775,128 to Roessingh, et al. issued Aug. 17, 2010 with the title “Cassette-based power meter,” and is incorporated herein by reference. In U.S. Pat. No. 7,775,128, Roessingh, et al. describe a cassette-based power-measuring apparatus having a power-sensing arrangement mounted within a cavity defined by a hollow bicycle sprocket cassette. Their power-sensing arrangement includes a torque-sensing assembly including torque-sensing elements configured to measure a user-applied torque. The torque-sensing elements communicate with an electronics assembly configured to process the measured data and transmit it to a receiver. The torque-sensing assembly may include a torque tube or a series of bending beams secured between a rear plate of the cassette and a freehub. The torque tube or bending beams may include strain gauges bonded thereto for measuring strain induced by application of forces in response to user-applied power.
U.S. Pat. No. 6,694,828 to Nicot issued Feb. 24, 2004 with the title “Torque sensor for a turning shaft,” and is incorporated herein by reference. In U.S. Pat. No. 6,694,828, Nicot describes a device having at least one magnetic-field generator placed on a first plane of a right section of a shaft and at least one magnetic-field detector placed in a second plane of a right section of the shaft. The detector produces a signal proportional to the torque following the relative angular shift of the field generator in relation to the detector, the magnetic-field generator having a magnetic structure supported by support mechanisms connected to the turning shaft. The magnetic field detector is located roughly opposite the magnetic field generator and is supported by support mechanisms connected to the turning shaft.